84 MANUAL OF POISONOUS PLANTS 



purposes the bulbs are usually collected between the decay of the foliage and 

 the production of the flowers. 



Opium is obtained from the capsules of the opium plant a few days after 

 the petals have fallen, the seed containing comparatively little of the narcotic 

 substances. It is well-known also that the poisonous principles of the Lark- 

 spurs are much more active in the spring than in the summer. Dr. Albert C. 

 Crawford x says referring to the Delphinium camporum, with which he con- 

 ducted some experiments and was able to kill several guinea pigs with toxic 

 material obtained from the plant collected on April 26th and May 16th, but 

 failed to get positive results of material collected in June. 



There is no question as to the fact that Delphinium when injected subcutaneously will 

 kill, and these experiments also establish the fact that the plant loses much of its toxicity as 

 it approaches the flowering stage. It has been noted that Delphinium consolida? is also less 

 active when mature. 



Just after flowering, the purple larkspur turns yellow and ceases to be attractive, so that 

 there is less danger of poisoning, although Chesnut and Wilcox report death in cattle from 

 eating Delphinium glaucum in September. The great danger early in the season seems to 

 arise from the fact that the Delphinium appears early in the spring, and the ground may again 

 be covered with snow, so that it is the only green plant in sight, and therefore when in an 

 especially poisonous stage it is eaten by cattle. 



Botanical and other writers have frequently called attention to the fact that 

 the greatest amount of poisoning in the west occurs in early spring- Of course, 

 this may be because there is less green food and live stock may consume more 

 of this plant than at other seasons. However, there seems scarcely any reason 

 to doubt that the plant does contain a larger amount of the acrid toxic sub- 

 stances in the spring than in the summer, as proved by the experiments of Dr. 

 Crawford. 



The same author who investigated the Mountain Laurel 3 calls attention 

 to the well-known fact that most of the cases of poisoning from Mountain 

 Laurel occur in the winter. Undoubtedly the animals will eat more of the 

 tough and leathery leaves in the winter because there is very little green for 

 them ; but may they not also have a larger amount of the toxic material ? The 

 plant is evidently also poisonous in the summer, as indicated by numerous re- 

 ports of the experiments by Dr. Crawford, who conducted an experiment with 

 material collected in the summer, in May and June, death occuring in a 

 sheep weighing 49 Ibs-, that had received 90 grams of powdered dried laurel 

 leaves. 



The late lamented Dr. Greshoff has called attention to the peculiar distribu- 

 tion of hydrocyanic acid in plants. In referring to a species of Hydrangea of 

 the Saxifragaceae he states that he sometimes found considerable quantities 

 of hydrocyanic acid in some of the well-known ornamental plants like the H. 

 hortensia and sometimes he did not find it He surmises that the cyanogentic 

 principle disappears from the leaves in the autumn and that the young leaves 

 have much more of the HCN than the older ones. In the case of the Plane 

 Tree (Platanus) he found considerable of the same acid in the young leaves 

 but as the leaves grow older the HCN content falls off to small traces. He 

 states further that in the ordinary plane tree of the London Streets there is so 

 much HCN that the amount from each London Plane Tree leaf would be enough 

 to kill a London sparrow. 



1 Bull. Bur. Plant Ind., U. S. Dept. of Agric. Ill: Part II; 7. 



2 Dammann, C. Gesundheitspflege. 1886:1072. 



3 Bull. U. S. Dept. of Ag., Bur. Plant Industry. 121:21. 



